Originally posted by einhander619
90 bps sounds a little more plausible, still nuts, though!
(GP)While it may be possible for pneumatic automation to function at 90 cycles per second, I don't think it very likely that a 'cocker can be made to do it if it is asked to fire the same as it would if shooting paint. That would be asking the valve to deliver enough air to get the ball to speed 5400 times per minute. (high speed, single barrel firearms can get up to about 1200 RPM but then the action has quite a bit farther to move too) Seems to me that if you add up the time it takes to move the sear; for hammer travel; for valve dwell, ram travel both ways and feeding, even with force feeding, there doesn't seem to be enough milliseconds to go around. Also, the bolt would have to be moving so fast that it would likely break every ball it tried to slap into the barrel. Maybe "Perfect Circle" plastic balls could stand it but I doubt normal paint would.
I think I'm going to forward this thread to my physics prof, he'll probably make a test question out of it. Even if a cocker did 90 bps, it probably couldn't sustain it for more than a few seconds before it would simply fly apart!
(GP) Probably not fly apart real quick if built half way decent; and with a buffered ram to absorb some of the shock force of the reciprocating mass. However, you couldn't expect much in the way of longevity. :-)
Now, Tom, I didn't do the math, but following your example, 90 cycles a second would take something on the order of around 600 psi input pressure to the ram, correct?
(GP) I think you will find that flow rate will be more of a factor to high cycling speeds than pressure numbers are.
It only takes about 10 pounds of force to cycle the action against the hammer spring and a standard 10mm ram will acomplish that at about 80 psi. LP pneumatic components are typically rated to 150 psi. Once you have enough force to overcome resistance, you only need adequate flow rate to get it done quickly. For example: Consider a big, pneumatic jack hammer (say a 90 pounder commonly used in construction) They cycle extremely fast, something near 4000 blows per minute (66 per second) but air input is very high volume at only about 125 to 150 psi.
So much for low pressure...